Changed my plugs now it does not run well?
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Joined: Jul 2011
Posts: 110
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From: MN
Year: 2001
Model: Cherokee
Engine: 4.0
the title says it all, I changed my spark plugs and now it barley runs and the chk engine light flashes? could the new plugs be bad? does the coil pack go bad if it is moved a lot? any help would be appreciated.
Thread Starter
Member
Joined: Jul 2011
Posts: 110
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From: MN
Year: 2001
Model: Cherokee
Engine: 4.0
Yes i took it off and re mounted it several times, I ended up running my finger down each to make sure they were seated.with it running i could see not sparking anywere.
one other thing the two center plugs (old ones that i took out) from the front of vehicle plug three wascorroded almost shut and plug 4 looked like it was gapped wide open almost like it blew open. yes I gapped the old ones when i put it in.
thanks for any help.
one other thing the two center plugs (old ones that i took out) from the front of vehicle plug three wascorroded almost shut and plug 4 looked like it was gapped wide open almost like it blew open. yes I gapped the old ones when i put it in.
thanks for any help.
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Member
Joined: Jul 2011
Posts: 110
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From: MN
Year: 2001
Model: Cherokee
Engine: 4.0
plug gap it .035
yes i hand seated (left the socket on and hand twisted that)
i did a light tighten. nothing two hard.
any sugestions and course of action to fix, as usual i am on a budget.
I was going to try new plugs again
then just get a new coil 105 from napa? I have never replaced but it looks pretty simple.?open to any suggestions?
yes i hand seated (left the socket on and hand twisted that)
i did a light tighten. nothing two hard.
any sugestions and course of action to fix, as usual i am on a budget.
I was going to try new plugs again
then just get a new coil 105 from napa? I have never replaced but it looks pretty simple.?open to any suggestions?
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Newbie
Joined: Mar 2013
Posts: 7
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From: Traverse City, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Make sure that if you are using your old plug wires, that when you removed your old/exsiting wires, that you didn't accidently pull the wire somewhat out of the boot. I've seen this happen a few times.
Senior Member
Joined: Sep 2008
Posts: 897
Likes: 12
From: Sioux Falls, SD
Year: 1999
Model: Cherokee(XJ)
Engine: 4.0L
I usually end up unplugging or bumping the various hoses on my '92 when I'm working on it. Double check all the hoses and sensor plugs. If possible, pull the computer codes. I found on my '92 that if the coolant-temp sensor is unplugged the engine will run like total crap.
I usually end up unplugging or bumping the various hoses on my '92 when I'm working on it. Double check all the hoses and sensor plugs. If possible, pull the computer codes. I found on my '92 that if the coolant-temp sensor is unplugged the engine will run like total crap. 

CF Veteran




Joined: Nov 2010
Posts: 5,841
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
If you did not have misfires BEFORE you installed the plugs, you gotta take another look at work performed. Maybe you have a spark plug that is cracked, etc. right out of the box. Rare, but I've seen it happen.
It would be best to get the codes read to see if you are dealing with one cylinder or more than one cylinder. Would be easier to focus on the problem that way. But if the check engine light is "flashing", it's not a great idea to drive it much as the flashing light indicates a serious misfire, which if ignored, will destroy your catalytic converter.
Know anyone with a code reader or a scan tool?
It would be best to get the codes read to see if you are dealing with one cylinder or more than one cylinder. Would be easier to focus on the problem that way. But if the check engine light is "flashing", it's not a great idea to drive it much as the flashing light indicates a serious misfire, which if ignored, will destroy your catalytic converter.
Know anyone with a code reader or a scan tool?
Last edited by tjwalker; Mar 18, 2013 at 10:54 AM.
Thread Starter
Member
Joined: Jul 2011
Posts: 110
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From: MN
Year: 2001
Model: Cherokee
Engine: 4.0
Well problem solved, I changed all the plugs again to a different brand, (not champion) same problem though not as bad but still had a little miss to I replaced the coil. Now with 187k it runs smoother than it ever has.
I think they gave me the wrong plugs the first time or they were defective. on three of the six the electrodes had been pushed down to almost touching? you could see brass markings on the top of the electrode were they had been pushed down. I thought i had done something wrong so I pulled out one of the new plugs i just installed and it was perfect and still gaped at .035. so I think it was a combo of the coil and plugs. thanks for all the input.
I think they gave me the wrong plugs the first time or they were defective. on three of the six the electrodes had been pushed down to almost touching? you could see brass markings on the top of the electrode were they had been pushed down. I thought i had done something wrong so I pulled out one of the new plugs i just installed and it was perfect and still gaped at .035. so I think it was a combo of the coil and plugs. thanks for all the input.
Senior Member
Joined: Apr 2012
Posts: 578
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From: Ocean, New Jersey
Year: 2000
Model: Cherokee
Engine: 4.0
Now that you fixed your immediate issue you need to address the bigger issue that got missed in your posts - rusted closed plugs 3 and 4. Keep a close eye on your coolant level. It looks like you're getting coolant leak right where the heads on 00-01 crack.
If you see coolant level drop with no external leaks, you need to address the root cause right away before your lower end is thrashed.
If you see coolant level drop with no external leaks, you need to address the root cause right away before your lower end is thrashed.


